Cuprodongchuanite

Chemical formula: Pb<sup>2+</sup><sub>4</sub>Cu<sup>2+</sup>Zn<sup>2+</sup><sub>2</sub>(PO<sub>4</sub>)<sub>4</sub>(OH)<sub>2</sub>

A very rare lead, copper, and zinc phosphate, forming characteristic blue rosette-like aggregates.

## Characteristics Cuprodongchuanite is a phosphate mineral, a copper analogue of dongchuanite. It forms thin, tabular or platy crystals of light blue to blue color. These crystals most often occur as radial clusters and aggregates resembling rosettes or fans, growing on a rock matrix. Due to the small size of the crystals, specimens are usually evaluated based on the entire aggregates. ## Physical Properties This mineral is characterized by a vitreous luster and is translucent. There is no precise data regarding its hardness and density, but it can be assumed that they are similar to other minerals in the tsumebite group. ## Colors and Varieties Cuprodongchuanite occurs in shades of blue, from light blue to more saturated tones. No color varieties or commercial names are known. ## History and Name The mineral's name refers to its chemical composition – the dominance of copper ("cupro") – and its structural relationship with dongchuanite. It was officially approved as a new mineral species by the International Mineralogical Association (IMA) in 2018. The name of the parent mineral, dongchuanite, comes from its discovery locality in the Dongchuan District, China. ## Applications Cuprodongchuanite, as an extremely rare mineral occurring in small quantities, has only scientific and collecting significance.

Properties

Luster
Vitreous
Streak
Light blue
Transparency
Translucent
Crystal system
Triclinic

Diagnostic features

## Identification The key identifying features of cuprodongchuanite are its characteristic light blue color, tabular crystal habit, and its tendency to form radial, rosette-like aggregates. Certain identification is also provided by knowing the origin – this mineral is known only from one locality in the world. ## Distinguishing from Similar Minerals Cuprodongchuanite can be confused with other blue secondary minerals, such as aurichalcite, linarite, or chalcedonite. However, aurichalcite forms acicular crystals, not tabular ones. Linarite usually has a much more intense, azure color. Visual distinction from the structurally similar dongchuanite is impossible without advanced chemical analyses (e.g., EDS), which can confirm the dominance of copper over zinc. ## Crystal Forms The mineral forms very thin, tabular crystals, which almost always occur in radial or fan-shaped clusters and aggregates, forming rosette-like shapes.

Geological environment

## Genesis Cuprodongchuanite is a secondary mineral, formed in the oxidation zone of polymetallic lead, zinc, and copper deposits. It crystallizes from phosphorus-rich hydrothermal solutions that react with ore minerals. ## Mineral Associations It most often co-occurs with other secondary minerals of the oxidation zone, such as cerussite, duftite, malachite, and willemite. ## Localities The only confirmed occurrence of cuprodongchuanite in the world is its type locality – Sanguozhuang in Dongchuan District (Yunnan Province, China).

Rarity

Extremely rare

For collectors

## Quality Criteria The most highly valued specimens are characterized by an intense, pure color, well-formed and clearly defined rosette-like aggregates, and a large coverage area on the matrix. Aesthetic composition with other associated minerals is also important. Due to the delicate nature of the crystals, the absence of any mechanical damage is crucial. ## Popular Localities The only source of collector specimens is the mine in Sanguozhuang in Dongchuan District, China. Material from this locality is highly sought after by specialized collectors of rare minerals.

Care and storage

## Cleaning Specimens should be cleaned with the utmost care, preferably using compressed air to remove dust. If necessary, a soft brush and distilled water can be used, avoiding strong rubbing. It should be dried immediately and thoroughly. ## What to Avoid The mineral is sensitive to acids and other strong chemicals, which can damage or destroy it. Ultrasonic cleaners and sudden temperature changes should be avoided. Prolonged exposure to direct sunlight is not recommended. ## Storage It is recommended to store specimens in closed, stable containers (e.g., micromount boxes) to protect them from dust, moisture, and mechanical damage. Due to the small size of the crystals, they are particularly susceptible to abrasion.

Sources

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